The present invention is directed to systems for processing strings and yarns. More particularly, the present invention is directed to surgical tipping apparatus for forming surgical suture tips through the use of ultrasonic welding.
Various automated systems for forming and cutting surgical suture tips exist or are known in the art. In one such machine, means for simultaneously advancing in parallel at least six separate strands of suture material, and six independent tensioners for maintaining respective parallel portions of each of the six strands at a preset tension are provided. Once a predetermined length of suture material has been advanced by the advancing means, a horizontal heater bar (positioned perpendicular to the six suture strands) is actuated by an electronically controlled solenoid which moves a planar heater bar into contact with one side of the suture strands for a predetermined dwell time. Once the predetermined dwell time has elapsed, the solenoid retracts the heater bar to its original position, and the heat exposed (or heat-stiffened) section of suture material is advanced to a cutting station. At the cutting station, the heat-stiffened section of suture material is cut at its midpoint, thereby producing a suture with two stiffened ends. Other mechanisms for forming and cutting surgical suture tips are shown in U.S. Pat. Nos. 4,832,025, 4,806,737 and 5,226,336 to Coates. The system described in the Coates patents uses convective or non-contact heating to form suture tips.
Known systems for forming and cutting surgical suture tips suffer from several drawbacks. First, such systems typically use heat to stiffen the surgical suture tips. Since the unfinished surgical suture material used by such systems is often coated, the heat applied during the tipping process may melt the coating. Once it has melted, the coating from the unfinished surgical suture material often adheres to the tipping machine, thereby compromising the machine""s performance. Another drawback of known systems for forming and cutting surgical suture tips is that such systems typically produce a suture tip, which lacks a substantially uniform cross-section.
In addition, such systems are undesirable in that they typically cut the suture tip in an imprecise manner, thereby leaving a cut end, which may be irregular or distorted in shape. From a manufacturing standpoint, suture tips having non-uniform cross-sections and/or irregular or distorted cut ends are undesirable because, among other things, such sutures are difficult to insert into needles. Finally, known systems, which use heat to stiffen surgical suture tips are undesirable because such systems cannot be used with sutures formed from silk.
It is therefore an object of the present invention to provide a system for forming surgical suture tips, which system does not use heat in forming the suture tips and which may be used to fuse silk.
It is a further object of the present invention to provide a surgical suture having a welded core, which facilitates the easy insertion of the suture tip into a needle.
It is a further object of the present invention to provide an automated system and method for manufacturing surgical sutures having tips with welded cores.
It is a still further object of the present invention to provide an automated system and method for making surgical sutures with tips having precisely cut ends.
It is yet another object of the present invention to provide an apparatus for tipping sutures and method for making suture tips.
These and other objects and advantages of the invention will become more fully apparent from the description and claims, which follow or may be learned by the practice of the invention.
The present invention is directed to a multifilament surgical suture having a body portion and a tip portion, which is adjacent to the body portion. The surgical suture is formed of a plurality of filaments. The tip portion has a tip length, a tip cross-section perpendicular to the tip length, and a tip core positioned at a center of the tip cross-section and along the tip length. The filaments positioned at the tip core are ultrasonically fused together.
In accordance with a further aspect, the present invention is directed to an apparatus for ultrasonically forming a surgical suture tip from a length of unfinished surgical suture material. The apparatus includes a first tipping die having a first face for contacting a portion of the length of unfinished surgical suture material. A second tipping die having a second face is also provided. At least one mechanical actuator is provided for moving the first face of the first tipping die toward the second face of the second tipping die. A second actuator vibrates at least one of the first and second tipping dies at an ultrasonic frequency of about 15 KHz to 70 KHz.
In accordance with a still further aspect, the present invention is directed to a method for ultrasonically forming a surgical suture tip from a length of unfinished surgical suture material. The length of unfinished surgical suture material is positioned at a location between a first face of a first tipping die and a second face of a second tipping die. After the positioning step, the surgical suture tip is formed by vibrating at least one of the first and second tipping dies at an ultrasonic frequency of about 15 KHz to 70 KHz.
In accordance with yet another aspect of the present invention there is provided an apparatus for ultrasonically forming a surgical tip from a length of surgical suture material. The apparatus comprises a first face, second face, third face, and fourth face. At least one mechanical actuators is provided for moving a first face and third faces toward the second face and fourth faces of the tipping apparatus. At least one of the dies is operably linked to a source of ultrasonic vibration in a frequency in the range of from about 15 KHz to 70 KHz.
In accordance with yet another aspect of the present invention there is provided a method for ultrasonically forming a surgical tip from a length of surgical suture material. A length of surgical suture material is positioned at a location between a first face and third faces of a first tipping die and a second face and fourth faces of a second tipping die. After the surgical suture material is in place the dies are contacted with the suture to shape the suture into the desired shape and at least one of the dies is vibrated at an ultrasonic frequency of about 15 KHz to 70 KHz.